It’s messier than that.
Shortly after Schlick arrived in Vienna in 1922, he was invited by the mathematicians Hans Hahn and Kurt Reidemeister to participate in a seminar on Principia Mathematica by Alfred North Whitehead and Bertrand Russell. At the same time he became acquainted with Ludwig Wittgenstein’s Logisch-Philosophische Abhandlung / Tractatus Logico-Philosophicus (1921/1922). In 1924 Schlick organized (at the request of his students Herbert Feigl and Friedrich Waismann) an extra-curricular discussion group, which came to be called the ‘Schlick Circle’ and after 1929 the ‘Vienna Circle’. Their first reading was Tractatus Logico-Philosophicus (Stadler 2001 [2015], Chs. 3, 4, 6). Soon Schlick was writing to Wittgenstein (Dec.12, 1924), seeking additional copies of his work, telling him about the study group in Vienna, and requesting personal meetings. This was not successful because Wittgenstein had left philosophy behind and worked as a school teacher in Lower Austria before he returned to Vienna in 1926 working as an architect for a house of his sister Margaret. But after several failed attempts, Schlick finally arranged with Wittgenstein’s sister, Margaret Stonborough-Wittgenstein to visit him in early 1927 (McGuinness 1967, 14). The first clear evidence that Schlick had obtained a copy of the Tractatus, which he had been reading and studying since 1922, was in a letters of Ludwig Hänsel, January 10 and 25, 1925 (Hänsel-Wittgenstein 1994, 92), later being confirmed to Einstein in June of 1927 (Schlick 1927a). The following month Schlick effusively described the Tractatus as “the deepest” work of the new philosophy (Schlick 1927b). Over the next few years Schlick and Wittgenstein, mostly together with Waismann till 1934, met as time permitted up to 1936, carrying on philosophical discussions ranging over a broad array of topics, from the idea of geometry as syntax, to verificationist and operationalist theories of meaning, topics in logic and mathematics, and even solipsism.
To give you a sense of Schlick:
In correspondence with Einstein Schlick explained that his monograph Raum und Zeit in der gegenwärtigen Physik was “less a representation of the general theory itself than a thorough-going elucidation of the thesis that space and time have now forfeited all objectivity in physics” … Schlick is referring to Einstein’s remark, in his 1916 paper on the General Theory, that the admission of arbitrary coordinative transformations “removes the last vestige of physical objectivity from space and time.”
Also:
The intuitive images of experience are spatially ordered, since they exhibit relative locations as well as spatial extension. In addition, since experiences occur one after another, they also exhibit an intuitive temporal order. This results in a distinct spatio-temporal ordering for each of the sense modalities, so that an intuitive order of smells, as well as an intuitive order of tastes (and so forth), is given in experience. The first step in the advance from purely subjective experiences to the transcendent ordering of scientific objects (according to his critical realism) is to coordinate the spatio-temporal frameworks of the distinct sense modalities. Thus, when a sore spot on one’s leg is touched by one’s forefinger, the feeling of the touch is accompanied by a visual image of the finger touching the leg. The coincidence of these two separate and distinct types of sensory data contributes evidence to the overall coordination of the spatio-temporal orders of the different sense modalities. This is the method of point-coincidences which Schlick used to characterize the advance from the purely subjective domain of qualitative images to knowledge of the transcendent world. Of course, the idea of point-coincidences also plays a central role in General Relativity, and it has generally been assumed that Schlick picked up the idea from his work on the new physics. But recent scholarship has demonstrated that, in fact, Schlick worked on the notion long before Einstein published the General Theory, and may well have been Einstein’s source for the notion (Engler 2009, 135ff). The important point in the present context is that the coordination of a single individual’s sense modalities is but the first step in the construction of the transcendent order. The next phase consists of the coordination of point-coincidences among different individuals. If an instructor wishes to draw attention to some feature of a triangle on a blackboard at the front of a class, he points to the feature, thus effecting a point-coincidence between the tip of his finger and the feature of the triangle. And even though everyone witnessing the demonstration has a different perspective, what they all share is their observation of the point-coincidence of fingertip and the geometric feature. Further, it is to be noted that not every sensory point-coincidence is an objective one, and not every objective point-coincidence is observed directly; it may be constructed or inferred from ones that are. Ultimately, all measurements, all determinations of space and time, are based on just such spatio-temporal point-coincidences.